Settings / Themes: Deleting hex color value in Edit mode locks up application.

[sirocyl]

Environment: Windows 10 v1809, all updates installed as of the posting of this issue.

Version: Release 0.7.2.0

Scope: Settings menu; Themes tab; Edit mode; any color's color picker.

Problem: When you delete the entire color value value and #, in the text entry in the color picker, the whole application locks up and becomes unresponsive, and sometimes crashes.
CPU usage is at 0% for all processes/threads of Fluent Terminal and its children.

Reproduction:

1. Start Fluent Terminal app, any profile, or minimized to tray.
2. Open the Settings window through any method (tray icon, hamburger menu)
3. Navigate to the Themes tab, and edit any editable theme.
4. Click on a color, to open the color picker.
5. Click at the end of the textbox for the hex color value, and backspace until there is only the # left.
   (Note: the app has not hung yet.)
6. Press backspace again. The # will remain in the textbox.
   After step 6, the app has hung, and might close out.

At step 5, clicking the "X" to clear the textbox has the same effect.

The first time this happened, the app was completely unresponsive, and needed to be ended from the Task Manager.
Upon reproducing this a second time, the app did close itself, and presumably crashed or was killed.

I did a cursory search of the issues here and did not see one which fit this description; if this is a duplicate, I'm sorry for wasting your time.

Attached below: reproduction of the issue in 20 seconds.

(Don't mind the scrollbar cursor where an edit/I-beam cursor would be; that's a bug in the capture software.)